Typically you have to configure the SMU in one of both modes: constant current or constant voltage. From there, depending on what is connected to the SMU determines what quadrant it falls into.
Quadrant operation examples:
- Quadrant 1: Force 3 V on the SMU, connect a resistor, positive current positive voltage (sourcing)
- Quadrant 2: Force 100 mA on the SMU, connect a 3V battery backward, positive current negative voltage (sinking)
- Quadrant 3: Force -3 V on the SMU, connect a resistor, negative current negative voltage (sourcing)
- Quadrant 4: Force -100 mA on the SMU, connect a 3V battery, negative current positive voltage (sinking)
Keep in mind all of these modes have limits, and if you hit the limit it'll transition into the other mode.
Constant voltage mode has a current limit, and if you hit it, it transitions into constant current mode to try and keep within that current limit.
Constant current mode has a voltage limit, if you hit it, it transitions into constant voltage mode to try and keep within that voltage limit.